Method and apparatus for the solidification of radioactive wastes and products produced thereby

Abstract

Methods for the encapsulation and solidification of waste material, particularly radioactive ion exchange resin bead media, are provided along with the apparatus to accomplish the methods, and the final encapsulated storage article. The ion exchange resin is solidified within a containment vessel by the addition of a thermosettable polymeric binder without the need for a pre-mixing vessel. The resulting exothermic conditions occasioned by the curing of the polymer are controlled by the sequential delivery of the polymeric binder, preferably through an injection lance.

We claim: 
     
       1. An improved method for encapsulating waste materials containing aqueous solutions, comprising: (a) providing a burial container having a waste material comprising radioactive ion exchange resin and an aqueous liquid disposed in the container, the container having a bottom section and an upper section;   (b) providing a polymeric binder comprising a thermosettable polymeric resin and a curing agent for the polymeric resin;   (c) initially introducing the polymeric binder into the ion exchange resin at a point proximate the bottom section of the container;   (d) subsequently, introducing the polymeric binder into the ion exchange resin at a plurality of points sequentially farther from the bottom section towards the upper section of the container; and   (e) curing the polymeric resin.   
     
     
       2. The method of claim 1 further comprising displacing aqueous liquid from the ion exchange resin prior to the introduction of the polymeric binder. 
     
     
       3. The method of claim 2 wherein the displacing is accomplished by introducing a hydrophobic liquid comprising a non-polar polymer into the ion exchange resin. 
     
     
       4. The method of claim 3 wherein the non-polar polymer comprises polyisobutylene. 
     
     
       5. The method of claim 4 wherein the polymeric resin comprises an epoxy resin and the curing agent comprises an amine compound. 
     
     
       6. The method of claim 5 further comprising creating a sub-atmospheric pressure condition in the container during the introduction of the polymeric binder. 
     
     
       7. The method of claim 1 further comprising providing an injection lance having a distal end and inserting the distal end of the lance into the ion exchange resin to a point proximate the bottom of the container, wherein the initial introduction of the polymeric binder into the container is through the distal end of the lance positioned at this point. 
     
     
       8. The method of claim 7 wherein the subsequent introduction of the polymeric binder is accomplished by withdrawing the lance from the container. 
     
     
       9. The method of claim 1 further comprising positioning the container in an orientation other than vertical prior to the introduction of the polymeric binder. 
     
     
       10. The method of claim 1 further comprising introducing the polymeric binder under an alternating positive pressure. 
     
     
       11. The method of claim 1 wherein the introduction of the polymeric binder is continuous. 
     
     
       12. The method of claim 1 further comprising controlling the temperature of the curing process below about 80° C. 
     
     
       13. An improved method for encapsulating radioactive ion exchange waste material containing aqueous solutions, comprising: (a) providing radioactive ion exchange resin waste material and an aqueous liquid in a burial container, the container having a bottom wall and an upper wall, and also providing a removable injection lance capable of carrying liquids positioned within the container, the lance having a distal end;   (b) providing a polymeric binder comprising a thermosettable polymeric resin and a curing agent for the resin;   (c) positioning the distal end of the lance at an injection point proximate to the bottom wall and introducing the polymeric binder into the .ion exchange resin through the lance;   (d) subsequently, repositioning the distal end of the lance within the container a plurality of times at points vertically above the previous injection point and again introducing the polymeric binder into the ion exchange resin; and   (e) curing the polymeric resin.   
     
     
       14. The method of claim 13 further comprising displacing aqueous liquid from the ion exchange resin prior to the introduction of the polymeric binder by adding a displacement solution comprising a non-polar hydrophobic polymer into the container proximate to the upper wall, the displacement solution having a density that is less than 1, and removing aqueous liquid from a point proximate to the bottom wall of the container. 
     
     
       15. The method of claim 14 wherein the displacement solution comprises polyisobutylene. 
     
     
       16. The method of claim 15 further comprising forcing the displacement solution in an upward flow within the container upon the introduction of the polymeric binder and withdrawing the displacement solution from the container at a point proximate to the upper wall of the container. 
     
     
       17. The method of claim 16 further comprising positioning the container in an orientation other than vertical prior to the introduction of the polymeric binder. 
     
     
       18. An improved storage article for the safe containment of radioactive waste ion exchange resin, comprising: a radioactive waste containment vessel containing a solidified matrix of polymerized epoxy-based resin within which is homogeneously distributed radioactive ion exchange resin and hydrophobic, non-polar polymer, wherein the non-polar polymer is chemically inert to the epoxy-based resin.   
     
     
       19. The article of claim 18 wherein the hydrophobic, non-polar polymer comprises polyisobutylene. 
     
     
       20. The article of claim 19 wherein the polyisobutylene forms a protective coating around the resin material thereby inhibiting chemical reaction between the resin material and the polymerized epoxy-based resin. 
     
     
       21. The article of claim 20 wherein the polymerized epoxy-based resin comprises epoxy resin and a amine curing agent for the epoxy resin.